TankBud

Round-tail paradise fish

Macropodus ocellatus

Also known as Chinese paradise fish, Roundtail paradisefish, Dark Knight Paradise Fish

FreshwaterFish

Round-tail paradise fish (Macropodus ocellatus)
Andrew Bogott · CC BY-SA 4.0

Care at a glance

Temperature
61–75°F
16–24°C
pH
6.0–7.5
Adult size
3.1 in
8 cm
Minimum tank
20 gal
75 L
Temperament
Mostly peaceful
Social behavior
Solitary
Tankmates
With caution
Swim level
Middle
Difficulty
Easy
Breeding
Bubble nester · Medium
Rarity
Common
Family
Osphronemidae
Origin
East Asia (China, Korea, Japan; Pearl River to Amur River basins)

Overview

The round-tail paradise fish is a cold-hardy, mostly peaceful fish for an unheated tank. It is an easy fish to keep.

Did you know

The round-tail paradise fish is one of the few aquarium fish that wants a real seasonal chill rather than steady warmth year round. A drop into the low teens Celsius over winter, followed by a slight warm-up, is what triggers it to spawn.

Caring for the round-tail paradise fish

Give round-tail paradise fish at least 20 gal (75 L), well planted, with floating plants, driftwood and leaf litter for cover. They need access to warm, humid air just above the waterline.

Treat this as a subtropical fish, not a tropical one, and leave the heater off. Keep the water at 61 to 75°F (16 to 24°C), with a pH of 6.0 to 7.5. They also benefit from a cool winter rest. Sustained tropical temperatures above roughly 24 to 25°C stress them and are linked to disease such as fish TB.

Feed small live and frozen foods, plus pellets and flakes. Males are territorial and turn aggressive toward their own kind and similar-shaped fish, especially when spawning. Keep one fish or a single pair, or use a large, heavily planted tank with broken sight lines rather than a true group.

The round-tail paradise fish is a bubble-nest builder, and the male tends the nest and fry. Breeding takes moderate effort.

In temperate climates, they do well in an outdoor pond over summer. Check your regional rules first, and never release any into local waters. Cold-hardy fish can establish themselves where they do not belong.

Good to know

The round-tail paradise fish, Macropodus ocellatus, is a labyrinth fish in the family Osphronemidae. Like other labyrinth fish, it has an accessory breathing organ and gulps air at the surface.

In the wild

Round-tail paradise fish come from East Asia, across China, Korea and Japan, from the Pearl River up to the Amur River basins. These are cool, slow waters that go cold in winter.

Common questions

What size tank does a round-tail paradise fish need?

A round-tail paradise fish needs at least 20 gal (75 L). It spends most of its time in the middle.

What temperature and pH does a round-tail paradise fish need?

A round-tail paradise fish is comfortable at 61–75°F (16–24°C) with a pH of 6.0–7.5.

What does a round-tail paradise fish eat?

A round-tail paradise fish eats small live and frozen foods, plus pellets and flakes.

How big does a round-tail paradise fish get?

An adult round-tail paradise fish reaches about 3.1 in (8 cm).

How does a round-tail paradise fish breed?

A round-tail paradise fish builds a bubble nest, and the male tends the nest and the fry. Breeding it takes moderate effort.

Related species